Psycholagny is a sexual term that refers to the ability to reach or achieve orgasm

Orgasm

Orgasm is the peak of the plateau phase of the sexual response cycle, characterized by an intense sensation of pleasure...

 without any physical stimulation

Sexual stimulation

Sexual stimulation is any stimulus that leads to, enhances and maintains sexual arousal, and may lead to ejaculation and/or orgasm...

 of the genitalia, usually achieved through mental stimulation or fantasy

Sexual fantasy

A sexual fantasy, also called an erotic fantasy, is a fantasy or pattern of thoughts with the effect of creating or enhancing sexual feelings; in short, it is "almost any mental imagery that is sexually arousing or erotic to [an] individual"...

alone. Also referred to as a "psychic orgasm" .

While this word is thought to almost never encountered outside of word lists, it is a concept in use among many adult lifestyle communities.